Page 305 - Atlas of Small Animal CT and MRI

3.2

Traumatic and vascular disorders

Vertebral column trauma tissues, and thin‐collimation and reformatted images
can aid fracture diagnosis. 5
Fracture/luxation It can be clinically useful to characterize thoracolum­
Fractures and luxations vary widely in location and bar vertebral fractures using a variation of the three‐
appearance but generally occur as a result of compressive, column model used in people. In this scheme, the dorsal
6
rotational, translational, hyperflexion, or hyperextension column includes the lamina, pedicles, and articular facets;
1
forces caused by blunt or penetrating trauma. Because the middle column includes the dorsal half of the vertebral
vertebral column injuries are often unstable, care should body; and the disk and the ventral column includes the
be taken to minimize patient movement even when ventral half of the vertebral body (Figure 3.2.1). In people,
image quality is compromised. Patients are often placed middle column trauma is more likely to be associated
on a backboard and maintained in lateral recumbency for with instability and neurologic deficits. 6
imaging studies. The most significant clinical questions
to address in patients with vertebral column trauma are Cervical vertebral fracture/luxation
whether spinal cord compression is present and whether Fractures occur less frequently in the cervical region
2,3
the injury is stable or unstable. Although survey radiog­ than in other parts of the vertebral column in dogs and
raphy is an excellent screening tool, sensitivity is only cats. When present, they most often involve the atlas
72% for fracture detection and 77.5% for subluxation (25%) or axis (52%), and multiple cervical vertebrae are
detection as compared to CT. Imaging studies should frequently affected. 7–10 Most cervical vertebral fractures
4
be viewed carefully and completely since a significant are caused by either automobile collision or bite injury,
minority of patients with vertebral fracture/luxation and almost half of these patients have other clinically
disorders sustain multiple injuries. significant injuries. 9
Fractures and luxations are both clearly delineated on
CT images, and multiplanar or 3D reformatting is often Occipital condylar fractures and luxations
useful to better characterize complex injuries. CT mye­ Occipital condylar fracture or atlanto‐occipital luxation
lography can be employed to define the presence and can occasionally occur as the result of high‐impact
extent of spinal cord compression due to fracture dis­ trauma and is associated with significant neurologic
placement or hemorrhage. Although MRI is superior to deficits (Figure 3.2.2). 11
CT for detecting spinal cord and other soft tissue injury,
it is less sensitive and specific for detecting and charac­ Atlantal (C1) fractures
terizing vertebral fractures or subluxations. Gradient Atlantal trauma caused by compression forces generally
echo volume‐acquisition sequences can be used to better results in multiple fractures through the body and arch
delineate bone (signal void) from surrounding soft and these are sometimes referred to as burst fractures

Atlas of Small Animal CT and MRI, First Edition. Erik R. Wisner and Allison L. Zwingenberger.
© 2015 John Wiley & Sons, Inc. Published 2015 by John Wiley & Sons, Inc.
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